This report summarizes the key technical issues from presentations and discussions that occurred at the workshop. This workshop summary is intended for informed scientists and policy makers as well as interested parties who are well versed on the issue of greenhouse gases, but it covers a range of technical material and thus is not intended as an introduction to the topic of carbon fluxes. This summary is intended to illuminate issues, not resolve them. By its nature, any workshop is necessarily incomplete, and a workshop summary can report only on what was said. With the exception of a few boxes and some cited references that are provided for context and background information, all of the information reported here emerged from presentations and discussions during the workshop. This summary is intended to reflect the variety of opinions expressed by the speakers.

Following this introduction, which describes the context, motivation, and goals for the workshop, Chapter 2 provides a summary of three policy perspectives, focused on national and international activities related to quantifying and reporting direct and indirect human-induced effects on carbon fluxes. Chapter 3 summarizes the science base regarding direct, indirect, and natural effects on carbon fluxes. The workshop speakers provided detailed discussions of the state of knowledge with regard to direct and indirect human-inducted effects, natural effects, and historical land use, reflecting both forestry and agricultural practices. The speakers also presented approaches for partitioning direct from indirect and natural effects. Chapter 3 also summarizes several presentations highlighting data and research needs in this field. Finally, Chapter 4 presents a synopsis of the ideas presented at the workshop, organized according to the five workshop goals presented in Box 1-4.